The target of rapamycin complex 2 controls dendritic tiling of Drosophila sensory neurons through the Tricornered kinase signalling pathway

To cover the receptive field completely and non‐redundantly, neurons of certain functional groups arrange tiling of their dendrites. In Drosophila class IV dendrite arborization (da) neurons, the NDR family kinase Tricornered (Trc) is required for homotypic repulsion of dendrites that facilitates dendritic tiling. We here report that Sin1, Rictor, and target of rapamycin (TOR), components of the TOR complex 2 (TORC2), are required for dendritic tiling of class IV da neurons. Similar to trc mutants, dendrites of sin1 and rictor mutants show inappropriate overlap of the dendritic fields. TORC2 components physically and genetically interact with Trc, consistent with a shared role in regulating dendritic tiling. Moreover, TORC2 is essential for Trc phosphorylation on a residue that is critical for Trc activity in vivo and in vitro. Remarkably, neuronal expression of a dominant active form of Trc rescues the tiling defects in sin1 and rictor mutants. These findings suggest that TORC2 likely acts together with the Trc signalling pathway to regulate the dendritic tiling of class IV da neurons, and thus uncover the first neuronal function of TORC2 in vivo.     

Highly purified eicosapentaenoic acid prevents the progression of hepatic steatosis by repressing monounsaturated fatty acid synthesis in high-fat/high-sucrose diet-fed mice

Eicosapentaenoic acid (EPA) is a member of the family of n-3 polyunsaturated fatty acids (PUFAs) that are clinically used to treat hypertriglyceridemia. The triglyceride (TG) lowering effect is likely due to an alteration in lipid metabolism in the liver, but details have not been fully elucidated. To assess the effects of EPA on hepatic TG metabolism, mice were fed a high-fat and high-sucrose diet (HFHSD) for 2 weeks and were given highly purified EPA ethyl ester (EPA-E) daily by gavage. The HFHSD diet increased the hepatic TG content and the composition of monounsaturated fatty acids (MUFAs). EPA significantly suppressed the hepatic TG content that was increased by the HFHSD diet. EPA also altered the composition of fatty acids by lowering the MUFAs C16:1 and C18:1 and increasing n-3 PUFAs, including EPA and docosahexaenoic acid (DHA). Linear regression analysis revealed that hepatic TG content was significantly correlated with the ratios of C16:1/C16:0, C18:1/C18:0, and MUFA/n-3 PUFA, but was not correlated with the n-6/n-3 PUFA ratio. EPA also decreased the hepatic mRNA expression and nuclear protein level of sterol regulatory element binding protein-1c (SREBP-1c). This was reflected in the levels of lipogenic genes, such as acetyl-CoA carboxylase α (ACCα), fatty acid synthase, stearoyl-CoA desaturase 1 (SCD1), and glycerol-3-phosphate acyltransferase (GPAT), which are regulated by SREBP-1c. In conclusion, oral administration of EPA-E ameliorates hepatic fat accumulation by suppressing TG synthesis enzymes regulated by SREBP-1 and decreases hepatic MUFAs accumulation by SCD1.     

Bioorganic synthesis of a recombinant HIV-1 fusion inhibitor,SC35EK,with an N-terminal pyroglutamate capping group

The bioorganic synthesis of an end-capped anti-HIV peptide from a recombinant protein was investigated. Cyanogen bromide-mediated cleavage of two Met-Gln sites across the target anti-HIV sequence generated an HIV-1 fusion inhibitor (SC35EK) analog bearing an N-terminal pyroglutamate (pGlu) residue and a C-terminal homoserine lactone (Hsl) residue. The end-capped peptide, pGlu-SC35EK-Hsl, had similar bioactivity and biophysical properties to the parent peptide, and an improved resistance to peptidase-mediated degradation was observed compared with the non-end-capped peptide obtained using standard recombinant technology.     

Molecular phylogenetic studies of Lachnum and its allies based on the Japanese material

Molecular phylogenetic studies were carried out based on ITS-5.8S rDNA, the D1–D2 region of the large subunit rRNA gene, RPB2, and combined data of D1–D2 and RPB2 as well as these three genes on 36 species among 7 genera for Lachnum and allied genera in the family Hyaloscyphaceae. In the combined data of all three regions, seven strongly supported clades were obtained. The same clades were also recognized in most of the trees based on each gene, and the combined data of D1–D2 and RPB2, although some of them were not strongly supported. Four clades represented Albotricha, Brunnipila, Incrucipulum, and Lachnellula, respectively, whereas Lachnum was distributed to the remaining three clades. The molecular phylogenies strongly supported a group of species with granulate hairs, and we suggest the concept of Lachnaceae should be restricted to these species. Based on the molecular phylogenetic analysis, three new combinations—Incrucipulum longispineum, I. radiatum, and Lachnellula pulverulentum from Lachnum—are proposed.     

Coordinated and Cohesive Movement of Two Small Conspecific Fish Induced by Eliciting a Simultaneous Optomotor Response

Background

In animal groups such as herds, schools, and flocks, a certain distance is maintained between adjacent individuals, allowing them to move as a cohesive unit. Proximate causations of the cohesive and coordinated movement under dynamic conditions, however, have been poorly understood.

Methodology/Principal Findings

We established a novel and simple behavioral assay using pairs of small fish (medaka and dwarf pufferfish) by eliciting a simultaneous optomotor response (OMR). We demonstrated that two homospecific fish began to move cohesively and maintained a distance of 2 to 4 cm between them when an OMR was elicited simultaneously in the fish. The coordinated and cohesive movement was not exhibited under a static condition. During the cohesive movement, the relative position of the two fish was not stable. Furthermore, adult medaka exhibited the cohesive movement but larvae did not, despite the fact that an OMR could be elicited in larvae, indicating that this ability to coordinate movement develops during maturation. The cohesive movement was detected in homospecific pairs irrespective of body-color, sex, or albino mutation, but was not detected between heterospecific pairs, suggesting that coordinated movement is based on a conspecific interaction.

Conclusions/Significance

Our findings demonstrate that coordinated behavior between a pair of animals was elicited by a simultaneous OMR in two small fish. This is the first report to demonstrate induction of a schooling-like movement in a pair of fish by an OMR and to investigate the effect of age, sex, body color, and species on coordination between animals under a dynamic condition.     

Improvement in Double Staining With Fluoro-Jade C and Fluorescent Immunostaining: FJC Staining Is Not Specific to Degenerating Mature Neurons

Fluoro-Jade C (FJC) staining has been used to detect degenerating neurons in tissue sections. It is a simple and easy staining procedure and does not depend on the manner of cell death. In some experiments, double staining with FJC and fluorescent immunostaining (FI) is required to identify cell types. However, pretreatment for FJC staining contains some processes that are harsh to fluorophores, and the FI signal is greatly reduced. To overcome this issue, we improved the double staining protocol to acquire clear double-stained images by introducing the labeled streptavidin–biotin system. In addition, several studies indicate that FJC can label non-degenerating glial cells, including resting/reactive astrocytes and activated microglia. Moreover, our previous study indicated that degenerating mesenchymal cells were also labeled by FJC, but it is still unclear whether FJC can label degenerating glial cells. Acute encephalopathy model mice contained damaged astrocytes with clasmatodendrosis, and 6-aminonicotinamide-injected mice contained necrotic astrocytes and oligodendrocytes. Using our improved double staining protocol with FJC and FI, we detected FJC-labeled degenerating astrocytes and oligodendrocytes with pyknotic nuclei. These results indicate that FJC is not specific to degenerating neurons in some experimental conditions:     

Adipolin/C1qdc2/CTRP12 protein functions as an adipokine that improves glucose metabolism

Obesity is a major risk factor for the development of insulin resistance and type 2 diabetes. Adipose tissue secretes various bioactive molecules, referred to as adipokines, whose dysregulation can mediate changes in glucose homeostasis and inflammatory responses. Here, we identify C1qdc2/CTRP12 as an insulin-sensitizing adipokine that is abundantly expressed by fat tissues and designate this adipokine as adipolin (adipose-derived insulin-sensitizing factor). Adipolin expression in adipose tissue and plasma was reduced in rodent models of obesity. Adipolin expression was also decreased in cultured 3T3-L1 adipocytes by treatment with inducers of endoplasmic reticulum stress and inflammation. Systemic administration of adipolin ameliorated glucose intolerance and insulin resistance in diet-induced obese mice. Adipolin administration also reduced macrophage accumulation and proinflammatory gene expression in the adipose tissue of obese mice. Conditioned medium from adipolin-expressing cells diminished the expression of proinflammatory cytokines in response to stimulation with LPS or TNFα in cultured macrophages. These data suggest that adipolin functions as an anti-inflammatory adipokine that exerts beneficial actions on glucose metabolism. Therefore, adipolin represents a new target molecule for the treatment of insulin resistance and diabetes.     

Bifurcation analysis and effects of changing ionic conductances on pacemaker rhythm in a sinoatrial node cell model

The electrical excitation (action potential generation) of sinoatrial node (cardiac pacemaker) cells is directly related to various ion channels (pore-forming proteins) in cell membranes. In order to analyze the relation between action potential generation and ion channels, we use the Yanagihara-Noma-Irisawa (YNI) model of sinoatrial node cells, which is described by the Hodgkin-Huxley-type equations with seven variables. In this paper, we analyze the global bifurcation structure of the YNI model by varying various conductances of ion channels, and examine the effects of these conductance changes on pacemaker rhythm (frequency of action potential generation). The coupling effect on pacemaker rhythm is also examined approximately by applying external current to the YNI model.